A problem which continues to exist in building construction is the difficulty in making a nonload-bearing wall adequately fire and sound resistant. In a typical building construction a ceiling is formed by galvanized steel, fluted decking atop which a layer of concrete is poured to form the floor above. The fluted steel decking may, for example, be fabricated of eighteen gauge galvanized steel. The flutes, or concave, downwardly facing channels defined in the underside of the decking, are typically about three inches deep and about six inches wide.
Interior, nonload-bearing walls often pass transversely across the flutes. The beams at the tops of such walls are attached to the underside of the decking where the decking projects downwardly between the hollow flutes. Openings having cross-sectional areas equal to the areas of the flutes are thereby formed above the beams that are located at the top of nonload-bearing, interior walls. These openings form transverse passageways across the tops of the walls through which fire and sound can travel.
To prevent the spread of fire through the flutes formed by the decking above nonload-bearing, interior walls, fire-resistant insulation is packed in the flute openings created at the tops of the walls by the flutes. This fire-resistant insulation may be applied by spraying it into the flute openings from each side of the wall. When the insulation dries and congeals it clogs the flute openings at the top of the wall.
As long as the insulation remains in the flute openings, they remain blocked and the insulation prevents the spread of fire across the top of the wall. However, when a fire is burning within a building, it generates a considerable amount of smoke which is heated and expands. The smoke causes a great pressure within a room where a fire is burning. It is known that the pressure of smoke from a fire burning within a room literally blasts the fire insulation out of the flute openings atop the wall. When this occurs the fire can thereupon spread to an adjacent room over the top of the wall through the flute openings.
According to present building construction practice fire insulation is held within the tunnel cavities defined by the flutes of the decking by hand cutting the upper edges of the gypsum board wall panels to follow the corrugations of the decking. The wallboard panels forming the sides of the nonload-bearing walls provide a series of projections that block the flute tunnels from the opposite sides of the wall and thereby hold the insulation in place. However, this system for holding the insulation in position is extremely time consuming, laborious, and expensive.
Hand cutting of the upper region of the wall to follow the convolutions of the corrugated, fluted decking is extremely labor intensive. The labor cost in creating a scalloped upper edge at the top of the wallboard adds significantly to the cost of construction of the wall. Moreover, even if a template is used the hand cuts result in significant gaps remaining which must then be caulked. The process of caulking is also an extremely laborious, labor intensive process, particularly when it is necessary to follow the convolutions of the underside of the fluted decking.
Moreover, conventional caulking is not seismic resistant. That is, even if the caulking originally provides an effective barrier to air currents, if the building structure subsequently is subjected to seismic activity, the caulking crumbles and gaps that allow the passage of air currents are opened. When this occurs the wall no longer offers its original resistance to the spread of fire. As a result, it has not heretofore been possible to provide both seismic resistance and fire resistance in interior building walls that will meet the stringent building codes applicable to structures such as schools and hospitals.
Therefore, there is a need for a wall structure that will prevent the spread of fire and sound along the flutes of a ceiling, yet is also economical and efficient to install.